The resurrection is the main event and the ultimate point of the gospel. The crucifixion functions as the qualifier that shapes the meaning of the resurrection.
By itself, the crucifixion would be meaningless. It would amount to nothing but the unpleasant but forgettable death of some wandering preacher long ago at the hands of the powerful. Jesus of Nazareth would appear in fewer footnotes than Bar Kochba. It is only because of the resurrection that the crucifixion becomes meaningful. Thus the crucifixion is dependent on the resurrection for its meaning.
The resurrection is fundamentally meaningful, though its meaning is contextually qualified by the crucifixion. Resurrection requires death in order to become possible, and so its meaning is necessarily qualified by death; however, to require death is not to require crucifixion. If Jesus had lived to an old age and died with dignity reclining on a couch conversing with his followers (as Socrates did) and had then been resurrected by God, his resurrection would still be meaningful as Good News and therefore worthy of proclamation. But its meaning would have a different quality.
Thus the relation between resurrection and crucifixion is like that between noun and adjective. The resurrection is the locus of meaning, and the crucifixion is the quality of the meaning. The resurrection is the sine qua non of Christian faith; the crucifixion is the sine qua aliter.